Electronic memories are used in many electronic systems to store information, for example, in electronic systems such as a mobile phone, a tablet, a computer, a server, as well as electronic systems including a processor or having a need to store information. The memory may be controlled through memory commands, such as write commands and read commands, that are received by the memory over a command bus. The information to be stored may be written to the memory using write commands, and retrieved at a later time by reading the information from the memory using read commands.
The circuits of an electronic system, including the memory, often operate according to a common clock. As known, a memory may be operated at different clock frequencies, such as a relatively high clock frequency (e.g., greater than 500 MHz), as well as at a lower frequency, which may reduce power consumption. However, the memory may need to have different operating conditions for proper operation at the different clock frequencies. That is, the memory operating conditions may need to be changed when the clock frequency changes. In some cases, memory operating conditions related to receiving memory commands over a command bus should be changed prior to the change in clock frequency in order to maintain communication with the memory, and for the memory to continue to operate properly.
Typically, the memory includes mode registers that store parameter codes for various operating and control parameters that are used to set the operating condition for the memory. The parameter codes may be written to the mode registers by way of mode register write operations. Examples of operating and control parameters include parameters related to burst length, preamble and postamble length, read and write latencies, on-die termination settings, reference voltage settings, as well as others. Changing the memory operating condition may involve writing new parameter codes for the operating and control parameters before the memory can properly operate under a new conditions, for example, with a new clock frequency. Changing the parameter codes for the various operating parameters can require several mode register write operations, which can delay when the memory can operate under the new condition. Additionally, the parameter codes for some of the operating parameters may need to be changed at the same time in order to maintain control over the memory, further complicating operation of the memory under a new condition.